Apparatus for ejecting balls

ABSTRACT

A sports apparatus for ejecting balls, such as tennis, cricket, baseball and similar balls, to provide a service of balls for training practice or for playing a game. The apparatus comprises a framework, a hammer with a striking face and which is mounted for continuous rotational movement about a shaft mounted on the framework so that the striking face describes a circular path of movement, and a feeder device comprised of a pair of spaced feeder plates positioned so that the striking face of the hammer will pass between them and adapted to feed successive balls to be positioned in the path of movement of the striking face.

United States Patent [72] Inventors Brian G. C. White;

Derek W. Schroder, Johannesburg; Donald C. Logan, Randburg, Republic of South Afri [21 App]. No. 752,926

[22] Filed Aug. 15,1968

[45] Patented Mar. 16, 1971 [73} Assignee said Schroeder and said Logan assignors to said White [32] Priority Aug. 17, 1967 [33] Republic of South Africa [54] APPARATUS FOR EJECTING BALLS 6 Claims, 11 Drawing Figs. [52] 11.8.0 124/1, 124/30, 124/41, 124/50 [51] Int. Cl F41b 15/00 [50] Field of Search 124/4, 1, 6

[5 6] References Cited UNITED STATES PATENTS 2,057,599 10/1936 Serrano 273/29.1X FOREIGN PATENTS 23,100/29 10/1930 Australia 124/16 Primary Examiner-Richard C. Pinkham Assistant Examiner-William R. Browne Attorney Jacobi, Davidson, Lilling & Siegel ABSTRACT: A sports apparatus for ejecting balls, such as tennis, cricket, baseball and similar balls, to provide a service of balls for training practice or for playing a game. The apparatus comprises a framework, a hammer with a striking face and which is mounted for continuous rotational movement about a shaft mounted on the framework so that the striking face describes a circular path of movement, and a feeder device comprised of a pair of spaced feeder plates positioned so that the striking face of the hammer will pass between them and adapted to feed successive balls to be positioned in the path of movement of the striking face.

Patented Mar cb 16, 1971 S Sheets-Sheet 1 FIG/2..

Patented March 16, 1971 3,570,466

5 Sheets-Sheet 5 ElCllO.

APPARATUS FOR EJECTING BALLS BACKGROUND OF THE INVENTION FIELD OF THE INVENTION This invention relates or training an apparatus adapted to eject loose articles along a desired predetermined trajectory. More particularly the invention concerns an apparatus for ejecting balls, such as tennis, cricket, baseball, table-tennis, squash, or similar balls, along a desired trajectory, and which is suitable to be used for training practice, or also fortraining practice, or also for playing a game.

SUMMARY OF THE INVENTION According to the invention there is provided an apparatus suitable for ejecting balls, which comprises a hammer having a suitable striking face and a stern and mounted for continous circulatory movement, a feeder device adapted to feed a plurality of balls in succession in such a manner that a ball will be positioned in the path of movement of the striking face after two or more full circulations of the hammer, and drive means for driving the hammer.

The continuous circulatory movement may preferably be rotary movement about a rotational axis substantially normal to the longitudinal axis of the stem. Furthermore, the feeder device is preferably adapted to feed the balls in such a manner that successive balls will be positioned for striking after a suitable number of full rotations of the hammer, as described in more detail later on.

The rotation of the hammer may preferably be at a substantially constant velocity. Any suitable rotation speed may be used in practice, depending upon the force with which a ball is required to be stuck. it has been found that a rotation speed of about 300 r.p.m. gives favourable results with tennis balls, causing a tennis ball to be ejected over the length of a tennis court.

The hammer may comprise an elongated stem or arm, conveniently in the form of a metal rod or pipe, and having a striking head at one extremity. Preferably a counterweight is provided at or near the other extremity of the stem, and then the hammer may be mounted for rotation about an axis disposed intermediate of the ends of the stem and substantially normal to the longitudinal axis of the stem. The hammer may be mounted on a shaft, which is driven by suitable driving means, to rotate the hammer so that the striking head describes a circular path of movement.

According to a further feature of the invention, the feeder device may be timed with respect to the hammer, to deliver the balls at suitable intervals, so that a ball will be positioned within the path of movement of the striking head and will be struck after a suitable number of revolutions of the hammer. The arrangement may be such that a ball will be struck after every 12 revolutions of the hammer.

This feature of the invention, i.e. that the hammer completes a number of revolutions before and after striking a ball, has the advantage that the hammer regains its momentum lost by striking the previous ball, before striking the next ball. Furthermore, due to its continous movement, the hammer will conserve all the momentum it has immediately after striking a ball.

The feeder device may compriseengagement means rotating below an open bottom receptacle for the balls, to engage one ball at a time and to position it in the path of movement of the striking face to be struck. In one form, thefeeder device may comprise a pair of spaced plates, conveniently of circular shape, mounted on a shaft to permit passage of the striking head of the hammer between the plates during rotation of the hammer. The circular plates have peripheral cutout portions to define engagement hooks, the arrangement being such that a ball will be engaged between thcplates in the cutout portions, and the plates are totated by driving the shaft to position the ball in the path of the striking face. A suitable receptacle for the balls is positioned above the rotating plates, the receptacle having a discharge opening to permit balls to fall under gravity onto the rotating plates. As the cutout portions come in register with the discharge opening, a ball will drop into the cutout where it will be held to be displaced with the rotating plates to a position in the path of movement of the striking face of the hammer.

As already indicated, the hammer should then be mounted in such a position that the striking face will pass between the spaced plates of the feeder device, to hit the ball. I

According to a further feature of the invention, if it is found to be desirable in particular circumstances, the feeder device may be provided with blocking means adapted to block the feed of ball to the striking position, sp as tp emab;e tje rate pf ekectopm pf ba;;s frp, tje a aratis tp be regulated. For example, the blocking means may be adapted to block alternate balls from being fed to the striking position, so that the rate of ejection of balls will be retarded.

In one form the blocking means may comprise a composite lever having a sensing limb, a blocking limb and a retaining limb, the lever being pivotally mounted in the proximity of the feeder plates to pivot between a blocking position and an open position, the arrangement being such that the sensing limb will be displaced by a ball engaged in the feeder plates to cause displacement of the blocking limb into a position to block the feed of the next succeeding ball, and displacement of the retaining limb to engage retaining means provided to maintain the lever in the blocking position, and the lever will return to the open position to permit a ball to be fed when the retaining limb is released by the retaining means.

The retaining means may conveniently comprise a shoulder formation provided on the side face of a feeder plate, with which the retaining limb will engage upon displacement of the sensing limb, th eshoulder formation being of such configuration as to reain the retaining limb until a next succeeding ball is to be fed.

In another form, the blocking means may comprise a shaft arranged in the proximity of the feeder plates, driving means for rotating the shaft about its longitudinal axis in synchronisation with the feeder plates, and at least one blocking member provided on the shaft in such a position that the blocking member will cyclically be brought into a blocking position to block the feed of balls to the feeder plate as the shaft totates.

In yet another form, the blocking means may comprise a pair of cooperating sprockets, the driving sprocket being fixed on the drive shaft and the driven sprocket being journalled on the feeder device shaft and the latter sprocket having at least one cam formation, a blocking element normally positioned to block the feed of balls, the arrangement being such that the blocking element is actuated by the cam formation to be dis placed into the open position, and th etheratio between the sprockets being selected to effect actuation of the blocking element at a desired rate.

The size ratio of the sprockets may be selected at such a value that the blocking element will be opened after a predetermined number of revolutions of the drive shaft. Furthermore, the relative rotational speeds of the driven sprocket of the blocking means and the feeder plates of the feeder device may be selected in such a manner that the opening of the blocking element and the passing of the cutout portions of the feeder plates under the ball discharge opening, will coincide after a predetermined number of revolutions of the feeder plates. It will be understood that, by varying the size ratio of the sprockets and/or the number andposition of the cam formations, different feed rates of balls may be effected, as required in each case.

The receptacle for the balls may be of any suitable configuration to ensure regular and uninterrupted feeding of bof balls. In one form the receptacle may comprise an elongated narrow chute arranged at an inclination to ensure regular gravity feeding of the balls, and having an outlet at its lower end for releasing successive balls to the feeder device one at a time.

Any suitable drive means may beprovided for driving the hammer and the feeder device. For example, as already mentioned, the hammer and the feeder plates may be mounted on shafts, and the shafts may be driven by means of sprocket and chain drives. The sprockets may advantageously be selected to drive the hammer at a stepped-up speed, and the feeder device at a reduced speed. It has been found that the relation between the rotational speeds of the hammer and the feeder plates may advantageously be between about :1 and :1, preferably 12:1.

In one embodiment, three parallel shafts may be provided, the one carrying the hammer, the second carrying the feeder plates, and the third carrying two driving sprockets. Suitable ste-up and reducing driven sprockets may then be provided on the first and second shafts respectively, actuating means for driving the third shaft, and chains for driving the driven sprockets from the driving sprockets. The actuating means for the driving shaft may comprise manual means, such as a handle, or automatic means, such as an electric motor or a petrol or battery operated motor. If desired, the driving shaft may be driven with electric current taken from a normally available supply.

If desired, a revolution counter or similar device may be provided, for indicating the rotation speed of the various shafts. For example, a simple speedometer may be connected operatively to the first shaft, i.e. the shaft carrying the hammer. By maintaining a constant rotation speed of the hammer shaft with reference to the speedometer, a regular delivery of balls may be ensured, particularly in the case of manual operation of the apparatus.

The shafts may be mounted on a suitable frame structure, which may be closed by panelling or plating. If desired, the frame structure may be reduced to a minimum by using a sturdy casing, such as of a moulded synthetic plastic material, which may be reinforced with glass fibre. In that case, suitable bearings may be integrally moulded in the housing, for journalling the various shafts.

According to yet another feature of the invention, the hammer and feeder device may be adjustable relative to one another in lateral and vertical directions, to vary the direction of the trajectory of the ball. This is achieved by adjusting the hammer and feeder device relative to one another to permit the striking face to strike the ball off center in lateral or vertical senses. To this end, the hammer shaft and/or the feeder device shaft may be journalled by way of bearings housed in bearing housings which in turn are arranged slidably in fixed slippers, and adjustment means may be provided to adjust the hammer and/or feeder device shafts laterally by displacing the bearing housings slidably within the slippers. Vertical adjustments may be effected by adjustably mounted shafts.

Alternatively, suitable adjustable deflector faces may be provided across the trajectory of the ball, to deflect the ball in any desired direction. In one embodiment, the deflector faces may be provided by a tube through which the ball passes. By adjusting the axial positioning of the tube, the ball may be deflected in the required direction. Alternatively, the deflector faces may be provided by deflector plates mounted adjustably to bring about deflection of the ball as required.

Suitable control levers may be provided to adjust the relative positions of the hammer and/or feeder device, and/or to adjust the deflector surfaces. The control levers may be adapted for manual adjustment. Alternatively, adjustement of the relative positions of the hammer and/or feeder device, and/or of the deflector faces may be brought about by a system of cam faces operatively connected to one of the shafts and adapted to effect deflection of the balls in accordance with a predetermined programme.

If desired, the deflector surfaces may be suitably surfaced to impart a spinning motion to the ball. For example, the surfaces may be rubber coated, or may be roughened.

BRIEF DESCRIPTION OF THE DRAWINGS The invention and the manner in which it may be carried out in practice, will now be described by way of example with reference to the accompanying drawings.

In the drawings:

FIG. 1 is a side elevation of an apparatus acording to the invention, shown with its casing removed;

FIG. 2 is a front elevation of the apparatus in the direction ofarrow A in FIG. 1;

FIG. 3 is a top plan view of the apparatus with the feeding chute and actuating handle removed;

FIG. 4 is longitudinal section on an enlarged scale, along line IV-IV in FIG. 1, with the feed chute and frame base portion not shown and the hammer shown partly in full;

FIG. 5 is a cross-sectional view, on an enlarged scale, of the adjustment means 70, taken along line V-V in FIG. 4;

FIG. 6 is a diagrammatic side elevation of one form of blocking the feed of balls, shown in the open position;

FIG. 7 is a diagrammatic side elevation corresponding to FIG. 6 but shown in the blocking position;

FIG. 8 is a diagrammatic side elevation of another form of blocking means for blocking the feed of balls, shown in the closed position;

FIG. 9 is a diagrammatic top plan view corresponding to FIG. 8 but with the outlet of the feed chute removed;

FIG. 10 is a diagrammatic plan view of yet another form of blocking means for blocking the feed of balls, in the open position; and

FIG. 11 is a diagrammatic plan view corresponding to FIG. 10, but shown in the closed position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, an apparatus for ejecting balls, e.g. tennis balls, comprises a light tubular framework 10 on which are journalled three shafts 12, 14 and 16. On the shaft 12 there is mounted a small sprocket 18 and a larger sprocket 20; on the shaft 14 there is mounted a small sprocket 22; and on the shaft 16 there is mounted a large sprocket 24. A handle 26 is provided on the shaft 12 for driving the shaft 12 and thus the sprockets 18 and 20.

In practice, the framework 10 may be covered by suitable casing, such as of a synthetic plastic material for safety reasons and also to present a neat appearance. In this connection it should be understood that, if a sturdy casing is provided, for example made of moulded glass fibre reinforced synthetic plastic material, the framework may be dispensed with partly or entirely. In this case, suitable bearings may be moulded integrally with the casing for journalling the shafts 12, 14 and 16. The various other parts may then also be supported directly on the casing.

Furthermore, instead of having a manually operated drive (i.e. handle 26), automatic drive means (not shown), such as an electric motor or a petrol or battery operated motor, may be employed d for driving the shaft 12. In suitable cases, the shaft 12 may also be driven with electric current taken from an available supply of electric power.

A chain drive 28 is provided between the sprockets 20 and 22, so that the sprocket 22 (and thus the shaft 14) will be driven at an increased rotational speed. A further chain drive 30 is provided between the sprockets 18 and 24, so that the sprocket 24 (and thus the shaft 16) will be driven at a reduced rotational speed.

On the shaft 14 there is further mounted a hammer having a striking face 32, a stem 34, and a counterweight 36. It is evident that the hammer will be rotated at a comparatively high rotational speed, with the striking face 32 describing a circular path of movement indicated by the arrow B.

On the shaft 16 there is mounted a feeder device comprising a pair of spaced plates 38a, 3838b having cutout portions to engage and carry a ball as shown at 40 (see FIGS. 4 and 7). It will be evident that the plates 38a, 38b are rotated at a comparatively small rotational speed. In practice, the speed ratio between the sprocket 22 and the sprocket 24 may be 12:1. The relative arrangement of the hammer and the feeder device is such that the striking face 32 of the hammer will pass between the feeder plates 3750. 381; during rotation of the hammer, to strike a ball carried in the cutout portions of the feeder plates. The ball will thus be ejected from the apparatus, along arrow D.

An elongaed narrow chute 42 having a discharge 44 is located above the feeder device, the chute 42 being arranged at an inclination for gravity feeding balls to the feeder device. The lateral dimensions of the chute 42 are such that a single row of balls is accommodated in the chute (as shown in FIG. 2), so that the balls willbe fed one at a time to the feeder plates 384,381).

A revolution counter in the form of a speedometer 45 is operatively connected via calbe 46 to the shaft 14. By maintaining the rotation of the shaft 14 at a constant speed with reference to the speedometer 45 (particularly in the case of a manually operated apparatus), a regular delivery of balls may be ensured.

As indicated before, the hammer and feeder device may be mounted in such a manner as to permit relative lateral and/or vertical adjustment, so as to enable the trajectory of the ball to be adjusted. Alternatively, or in addition to the foregoing, one or more deflector plates may be provided, which are so positioned as to permit the ball to impinge against them to deflect its course of flight. In the following paragraphs, the relative adjustment of the hammer and feeder device, and the operation of the deflector plates will be described in more detail.

In order to adjust the flight of the balls in the vertical sense, a deflector or lob plate 48 is provided at the point of exit of the balls from the apparatus. The plate 48 is pivoted on the frame structure at 50, to permit up-and-down displacement of the plate 48. A lever system 52, 54, 56 connectws the plate 48 to a lever 58 which in turn is pivoted at 60. By displacing the lever 58 in an upward or downward direction, the deflector or lob plate 48 can be adjusted vertically. An arcuate holed member 62 is connected to the plate 48, and by securing the member 62 to a frame member by means of the wingnut 64, the plate 48 can be locked in a particular position, if desired.

It will be understood that, when the deflector or lob plate 48 is positioned as shown in borken lines in FIG. 1, to extend obliquely across the path of aball, the ball will impinge against the plte 48 and will e be deflected upwardly, to simulate a high ball.

If desired, the plate 48 may be suitably surfaced, i.e. by having a rubberised or roughened surface, to impart a spinning motion to the ball.

In order to adjust the flight of the balls in the lateral sense, the alignment of the hammer relative to the feeder plates 38a, 38b, and consequently relative to a ball carried by the feeder plates, is varied. This is achieved by mounting the hammer shaft 14 (see FIGS. 4 and 5) by way of suitable bearings housed in a bearing housing 66, within slippers 68, such that a bearing housing 66 can slide within a slipper 68. The hammer shaft 14 is adjusted laterally by causing the bearing housings 66 to slide in the slippers 68, with the aid of an adjustment mechanism generally indicated as 70 inFIGS. l and 4.

As shown in FIG. 5, the adjustment mechanism 70 comprises a spherical element 72 fixed to the bearing housing 66. A bolt 74 passes through the spherical member 72, and also through the end region of a torque tube 76. The other end of the torque tube 76 passes through a bush 78 fixed to the frame structure 18, and is secured by e means of a T-joint to the for ward end of the handle 58 as at 60. By displacing the handle 58 in lateral direction to either side, the torque tube 76 is rotationally displaced as shown by the arrow C in FIG. 5, and this movement is transferred via h the bolt 74 and spherical member 7 2 to the bearing housing 66 and shaft 14, to displace the bearing housings 66 slidably within teh slippers 68 t and so to displace the shaft 14 and hammer laterally relative to the feed plates 38a, 38b and the ball.

The hammer can thus be positioned to strike the ball off center, and so to eject the ball in a sidewardly deflected path.

According to a further feature of the apparatus, blocking means is provided to block or halt the feed of balls to the feed plates 38a, 38 b and so to retard the rate of ejection of the balls. One embodiment of a blocking device is shown diagrammatically in FIGS. 6 and 7. The blocking device comprises a lever pivoted at 80 and having a sensing limb 82, a blocking limb 84, and a retaining limb 86. A shoulder formation 88 is provided on the side of one feeder plate 380. When a ball is in position on the feeder plates 38a, 38b as shown at 40 in FIG. 7, the sensing limb 82 is lifted, and the retaining limb 86 is brought into engagement within the shoulder 88, and the blocking limb 84 is broght into the blocking position to block the feed of balls. As the feed plate 38a'rotates, the retaining limb 86 is retained in the shoulder formation 88, and the blocking limb 84 is retained in the blocking position. When the retaining limb 86 reaches the end of the shoulder formation 88, it is relased, and the lever swings downwardly about the pivot 80 under its own weight. Thereby the blocking limb 86 is displaced into the open position as shown in FIG. 6, and a ball is fed to the feed plates 38a, 38b.

Depending upon the configuration of the shoulder formation 88, the blocking means can be retained in the blocking position for a predetermined number of revolutions of the feeder plates 38a, 38b.

An alternative embodiment of the blocking means is shown in FIGS. 8 and 9, which comprises an upright shaft 90 operatively connected via gears 92, 94 to the shaft 16 of the feed plate 38a, and being proivded with a blocking element 96. The arrangment is such that the shaft 90 will rotate with the feed plates 38a, 38b, to position to block off the feed of balls, and in an open position to permit balls to be fed to the feed plates 38a, 38b, to position the blocking element 96 alternately in a blocking position to block off the feed of balls, and in an open position to permit balls to be fed to the feed plates 38a, 38b. Depending upon the gear ratio of the gears 92, 94 the blocking positiion can be brought about after a predetermined numbe of revolutions of the feed plates 38a, 38b.

As described above, in use a ball will be engaged by the feeder device and positioned in the path of movement of the striking face of the hammer after a number of revolutions of the hammer (e.g. 12 is the ratio is l2:las mentioned above. The ball will then be struck and ejected from the apparatus along a predetermined trajectory. Consecutive balls will be ejected after every 12 revolutions of the hammer.

Referring now more particularly to FIGS. 10 and ll, yet another emobidment of the blocking means for blocking the feed of balls is illustrated. The blocking means in this case comprises a pair of cooperating sprockets I00, 102, the smaller driving sprocket 100 being keyed to the drive shaft 12 and the larger driven sprocket 102 being journalled, such as by means of a sleeve or bush, on the shaft 16 carrying the feeder plates 38a, 38b. The sprocket 102 is driven by means of a chain 104, and it is provided with at least one cam formation 106 on its outside face.

A lever 188 is pivoted at on the frame structure 10, the free end of the lever 108 being spring loaded by tension spring 112, so that it is normally in the blocking position across the discharge 44 to block the feed of balls to the feeder plates 38a, 38b (see FIG. 11). When the cam formation I06 engages the lever 108 during the rotation of the sprocket 102, the lever 108 is displaced into the open position (as shown in FIG. 10), to permit a ball to be fed to the feeder plates 38a, 38b.

If desired, two or more cam formations may be provided on the sprocket 102, to open the blocking lever 108 two or more times during a single rotation of the sprocket 102.

It will be appreciated that a ball will only be carried to the striking position to be ejected, if the cutout portions of the feeder plates 38a, 38b occur in register with the ball discharge 44 at the same moment that the blocking lever 108 is dispaced into the open positon. Accoordingly, by selecting suitable size ratios of the sprockets I18, 24 driving the feeder plates 38a, 38b, relative to the sprockets 180, 102 actuating the blocking lever 108, a suitable phase difference may be brought about in the rotation of the sprocket 102 and the feeder plates 38a, 381; so that the cuout portions of the feeder plates 38a, 38b and the opening of the blocking lever 108 will only coincide after a predetermined number of revolutions of the drive shaft and feeder device, thereby regulating the feed rate of balls to the striking positon.

Iclaim:

1. Apparatus for ejecting balls, which comprises a framework, a first shaft mounted on the framework, a hammer having a stem mounted on the first shaft and a striking face mounted on the stem and adapted to perform continuous circulatory movement about the first shaft, drive means mounted on the framework for causing the circulatory movement of the striking gace, and a feeder device mounted on the framework above the first shaft for feeding a plurality of balls into the path of the striking face, said feeding device comprising an open bottom receptacle mounted on the framework, a second shaft mounted on the framework below the receptacle and a pair of plates of circular shape mounted on the second shaft for circulatory movement and spaaced apart to permit passage of the striking face of the hammer between them during rotation thereof, the said plates having peripheral cut out portions to define engagement hooks for engaging a ball between the plates in the cutout portions, drive means for causing circulatory movement of the plates and synchronization means for causing a ball to be positioned between the said plates in the path of the striking face after at least two full circulations of the hammer.

2. Apparatus according to claim 1, in which the receptacle for the balls is positioned immediately above the rotating plates, the receptacle having a discharge opening to permit balls to fall under gravity onto the rotating plates.

3. Apparatus according to claim 2, in which the receptacle comprises an elongated narrow chute arranged at an inclination to ensure regular gravity feeding of the balls, and having outlet at its lower end for releasing successive balls to the feeder device one at a time.

4. Apparatus according to claim 1 in which the feeder device contains a removable blocking means adapted to block the feed of balls to the pair of plates when in the blocking positon.

5. Apparatus according to claim 1, in which a third shaft is mounted on the framework with said first, second and third shafts parallel to each other, and in which the drive means for causing circulatory movement of the plates and to of the striking face of the hammer comprises chain drives from the sprockets on the first and second shafts to the sprockets on the third shaft, actuating means being provided for driving the third shaft.

6. Apparatus according to claim 5, in which a ball-feed blocking means is provided adjacent of the feeder device, said ball-feed l blocking means being adapted to block the balls being fed to a ball striking position, the blocking means comprising a pair of cooperating driving and driven sprockets, the driving sprocket being fixed on the said third shaft and the driven sprocket being journaled on the said second shaft with the driven sprocket a having a at least one cam formation thereon a blocking element normally positioned to block the feed of balls and displaceable into an open position to permit the feed of balls, the blocking element being actuated by the cam formation to be displaced into the open position, and the ration between the sprockets being selected to effect acutation of the blocking element at a desired rate. 

1. Apparatus for ejecting balls, which comprises a framework, a first shaft mounted on the framework, a hammer having a stem mounted on the first shaft and a striking face mounted on the stem and adapted to perform continuous circulatory movement about the first shaft, drive means mounted on the framework for causing the circulatory movement of the striking gace, and a feeder device mounted on the framework above the first shaft for feeding a plurality of balls into the path of the striking face, said feeding device comprising an open bottom receptacle mounted on the framework, a second shaft mounted on the framework below the receptacle and a pair of plates of circular shape mounted on the second shaft for circulatory movement and spaaced apart to permit passage of the striking face of the hammer between them during rotation thereof, the said plates having peripheral cut out portions to define engagement hooks for engaging a ball between the plates in the cutout portions, drive means for causing circulatory movement of the plates and synchronization means for causing a ball to be positioned between the said plates in the path of the striking face after at least two full circulations of the hammer.
 2. Apparatus according to claim 1, in which the receptacle for the balls is positioned immediately above the rotating plates, the receptacle having a discharge opening to permit balls to fall under gravity onto the rotating plates.
 3. Apparatus according to claim 2, in which the receptacle comprises an elongated narrow chute arranged at an inclination to ensure regular gravity feeding of the balls, and having outlet at its lower end for releasing successive balls to the feeder device one at a time.
 4. Apparatus according to claim 1 in which the feeder device contains a removable blocking means adapted to block the feed of balls to the pair of plates when in the blocking positon.
 5. Apparatus according to claim 1, in which a third shaft is mounted on the framework with said first, second and third shafts parallel to each other, and in which the drive means for causing circulatory movement of the plates and to of the striking face of the hammer comprises chain drives from the sprockets on the first and second shafts to the sprockets on the third shaft, actuating means being provided for driving the third shaft.
 6. Apparatus according to claim 5, in which a ball-feed blocking means is provided adjacent of the feeder device, said blocking means being adapted to block the balls being fed to a ball striking position, the blocking means comprising a pair of cooperating driving and driven sprockets, the driving sprocket being fixed on the said third shaft and the driven sprocket being journaled on the said second shaft with the driven sprocket a having a at least one cam formation thereon a blocking element normally positioned to block the feed of balls and displaceable into an open position to permit the feed of balls, the blocking element being actuated by the cam formation to be displaced into the open position, and the ration between the sprockets being selected to effect acutation of the blocking element at a desired rate. 